【作者】 代大海；

【导师】 肖顺平；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2008， 博士

【摘要】 本论文紧密结合973国家安全重大基础研究项目“雷达自动目标识别新机理新方法研究”、国家自然科学基金重点项目“雷达极化信息获取与处理”以及国防预先研究项目“雷达目标高分辨极化特性研究”等,针对高分辨极化雷达体制,深入开展了极化雷达成像及目标特征提取方法的研究工作,主要内容包括全极化测量条件下高分辨成像、目标散射中心特征参数估计及其性能分析、典型有源干扰下的SAR成像方法等。需要特别指出的是,本文提出的基于相干极化散射模型的高分辨极化矢量信号处理的思想与方法,突破了传统的多极化分通道进行处理的思路,不仅能更加准确地估计目标的特征参数,而且有效解决了传统方法中的散射中心位置、极化的关联处理等难题,处理效率更高、效果更优。考虑到未来战场越来越复杂的电磁环境,论文还研究了随机极化压制干扰和有源假目标欺骗干扰两种典型干扰条件下的极化SAR(PolSAR)成像方法。第一章首先概述了雷达极化学的发展历程、研究内容和发展趋势,重点介绍了极化雷达成像及目标特征提取方法的研究现状,归纳了高分辨极化信息处理的特点和优势,简要阐述了论文的主要研究内容。第二章研究了目标全极化散射中心特征参数估计及其性能分析问题。针对相干极化理想点散射模型,首次推导并得到了模型参数(包括散射中心位置、散射矩阵元素的幅度、相位、相位差等)估计的极限性能,得出了极限估计精度与带宽、信噪比、极化等因素的解析关系,证明了在散射中心参数估计方法的极限精度方面,全极化处理优于任意单极化处理;提出了极化多重信号分类方法(P-MUSIC)和极化旋转不变子空间方法(P-ESPRIT)两种性能优良的全极化散射中心参数估计方法,并分别利用仿真和实测数据进行了验证和阐释。第三章研究了色散条件下目标全极化散射中心参数估计与性能分析问题。首先建立了雷达目标的相干极化几何绕射理论(CP-GTD)模型,该模型能够同时描述目标散射中心的频率色散特性和极化特性;提出了基于CP-GTD模型的目标散射中心特征提取与参数估计方法,从非相干性和相干性两个角度评估了其估计性能,通过仿真和实测数据实验,验证了CP-GTD方法的优越性;推导得到了CP-GTD模型参数估计的极限性能,分析了模型各参数估计性能与带宽、信噪比、极化等因素的约束关系,其结果可用于指导系统参数设计以及算法性能评价等方面;最后结合弹道导弹攻防的应用背景,提出一种新的弹道中段目标结构和微动特征提取方法。第四章研究了极化SAR/ISAR超分辨成像与目标特征提取问题。首先针对极化ISAR体制,建立了雷达目标的二维CP-GTD模型,提出了基于该模型的全极化ISAR超分辨成像及特征提取方法;从极化复图像域出发,提出了基于理想点散射模型的极化SAR超分辨成像与目标散射中心特征提取方法。利用仿真数据、暗室测量数据和实测PolSAR复图像数据,验证了这两种方法的有效性,其突出优点是不需要进行散射中心位置及极化的关联,并可以实现相干极化散射矩阵元素的同时估计。第五章研究了随机极化有源压制干扰和有源假目标欺骗干扰两种典型干扰下的极化雷达成像方法。在对抗随机极化有源压制干扰的成像方法中,提出了级联极化变换的概念和方法,研究了时变随机极化干扰的统计特性,提出了基于极化变换滤波的抗干扰方法,突破了“传统极化滤波对随机极化干扰在功率上得益有限”的结论,利用实测SAR数据得到了满意的抗干扰成像效果。在对抗有源假目标欺骗干扰的成像方法中,提出了在多普勒域通过相位补偿来实现PolSAR有源假目标干扰鉴别和对消的成像方法,并利用实测SAR和仿真数据得到了有源假目标干扰下的良好成像结果。更多还原

【Abstract】 Sponsored by the State Key Development Program for Basic Research of China (973) of National Security (New Mechanism and New Methods of Radar Automatic Target Recognition), the Major Program of the National Natural Science Foundation of China (Radar Polarization Information Acquisition and Processing) and National Defense Pre-Research Foundation of China (Target Polarization Character of High-resolution Radar), this dissertation mainly focuses on the research of polarimetric radar imaging and target feature extraction. The research topics including the polarimetric super-resolution imaging, feature extraction of target scattering center and perform analysis of the extraction, SAR imaging formats under the typical jamming background. The most significant point is the idea and method, which is brought out based on the coherent polarization scattering model and high-resolution polarization vector signal processing, is a breakthrough compared with the traditional multi-channel processing method. This method can not only estimate the feature parameters more correctly, but also resolve the difficult problems in the traditional method including association processing of center locations and polarizations more effectively. So it is more effective and has better performance comparing with the traditional method. Considering the complex electromagnetic environment in the future warfare, the PolSAR imaging method under the random polarization jamming and active decoy condition is also studied.Chapter 1 introduces the current development of the radar polarization theory and methodology, especially the imaging and feature extracting techniques of polarimetric radar. The major research topics of this dissertation are explained in this chapter.Chapter 2 studies the feature parameter estimation of the fully polarized scattering center and analyses its performance. Firstly, the explicit expressions of the Cramer-Rao bounds (CRB) of fully polarized scattering centers are presented for the first time. Moreover, the CRBs of amplitude, phase and phase difference between two components of the scattering matrix are derived and expressed in closed forms for several typical cases together with their relation with the radar system parameters (the band width, SNR and polarization etc). Thereby, two novel methods of fully polarized scattering center extraction and parameter estimation, which called P-MUSIC and P-ESPRIT, are proposed. The validity of these two methods is proved by the experimental results based on simulated and real data.In Chapter 3, the parameter estimation method of the fully polarized scattering center under the dispersive condition is studied and its performance is analyzed. The CP-GTD can represent the frequency dispersion characteristics and the full-polarization characteristics of the target scattering center simultaneously. A novel scattering center extraction and parameters estimation method is proposed based on the CP-GTD. The performance of this method is evaluated using coherence and incoherence index and testified by the simulation and testing data. The superiority of the CP-GTD is verified in theory. The relation between the estimation performance of the model parameters and the band width, SNR and polarization etc is studied. This study provides a meaning theory guide to the engineering practice.Chapter 4 focuses on the problems of the fully polarized super-resolution imaging of SAR/ISAR and the target feature extraction. Firstly, the two-dimensional CP-GTD (2D CP-GTD) is established and the methods of super-resolution imaging and features extraction for polarimetric ISAR are studied based on 2D CP-GTD. In the polarimetric complex imaging space, the super-resolution imaging and target scattering center extracting methods of polarimetric SAR (PolSAR) are proposed based on the coherent polarization idea point scattering model. These methods are validated using simulation data, data measured in microwave anechoic chamber and practice measured PolSAR complex imaging data. Unlike the traditional method, these methods can estimate coherent scattering matrices of scattering centers accurately by overleaping the step of scattering center association. They also can estimate the elements of the coherence polarization scattering matrix simultaneously.In Chapter 5, the polarimetric radar imaging method under the random polarized suppression jamming and the active decoy condition is studied. The concept and method of serial polarization transform (PT) is proposed to suppress the random polarized blanket jamming. The suppression method is proposed based on the PT filter, which makes a breakthrough on the suppression effect of the traditional polarization filter. The satisfied anti-jamming imaging result is realized based on this method using the practice SAR data. The PolSAR image method, which can realize the active decoy distinguish and cancelling, is proposed to suppress active-decoys jamming. This imaging method is realized by phase compensation in Doppler domain. Its validity is proved by good imaging results under active decoy condition using the simulation and experimental SAR data.更多还原